Be more conservative about current buffer

void EglManager::requireGlContext() {

    LOG_ALWAYS_FATAL_IF(mEglDisplay == EGL_NO_DISPLAY, "No EGL context");

    // We don't care *WHAT* surface is active, just that one is active to give

    // us access to the GL context

    if (mCurrentSurface == EGL_NO_SURFACE) {

    // We can't be certain about the state of the current surface (whether

    // or not it is destroyed, for example), so err on the side of using

    // the pbuffer surface which we fully control

    usePBufferSurface();

}

}

void EglManager::loadConfig() {

    EGLint swapBehavior = mCanSetPreserveBuffer ? EGL_SWAP_BEHAVIOR_PRESERVED_BIT : 0;